1. Field of the Invention
The invention relates to chemical polishing of aluminum alloys. More specifically, it relates to a polishing bath composition including phosphoric acid, nitric acid, sodium nitrate and water.
2. Description of the Prior Art
Both patent literature and general scientific literature contain many references related ,to polishing aluminum. The Metal Finishing Handbook (Metals and Plastic Publishing Company) and Wernick and Pinner Surface Treatment of Aluminum, 4th Ed., 1974, pp. 120-146, discuss polishing at length. Prior art polishing methods cause the formation of smut on the surface of the workpiece which necessitates the use of additional process steps, either mechanical or chemical, to remove. These additional steps increase the total number of manufacturing steps and result in overall higher cost.